1. Field of the Invention
The present invention relates to a force sensor including a base substrate joined to a sensor substrate having a plurality of piezoresistance elements for load measurement, and relates to a method of manufacturing the force sensor.
2. Description of the Related Art
Nowadays, force sensors for load measurement are used in user interfaces such as touch panels and controllers of mobile devices. A known force sensor includes a sensor substrate having a pressure receiving unit, a displacement portion, a support, piezoresistance elements, and electrically connecting portions formed therein. An external load is applied to the pressure receiving unit, the displacement portion is displaced in accordance with the load applied to the pressure receiving unit, the support supports the displacement portion from a surface, which is on a side opposite to a side on which the pressure receiving unit is provided, such that the displacement portion can be displaced, the piezoresistance elements detect the amount of displacement of the displacement portion, and the electrically connecting portions are electrically connected to the piezoresistance elements. The force sensor also has a base substrate joined to the sensor substrate so as to be mounted on an external object. Specifically, the force sensor can be connected to external circuitry as follows: Electrode pads of the base substrate, which are connected in an electrically conductive manner to the electrically connecting portions of the sensor substrate, are electrically connected to external circuitry by wire bonding. Alternatively, a package, in which the electrically connecting portions of the sensor substrate are connected to the electrode pads of the base substrate in an electrically conductive manner by wire bonding, is provided and electrically connected to external circuitry. A force sensor having such a related-art structure has been disclosed in, for example, Japanese Unexamined Patent Application Publication No. 10-325772.